Abstract
For the purpose of developing new plastic filling materials instead of amalgams, various properties of gallium alloys based on 80%Sn-20%Cu which was added platinum, palladium and silver were investigated, and following conclusions were obtained.
1)Dimensional change of all gallium alloys satisfied ADAS No.1(±20μm/cm).The dimensional change was tended to decrease with the addition of platinum, palladium below 5 wt% and silver below 20 wt%.
2)Compressive strength at two days after mixing and dimensional change correlated inversely to each other. Compressive strength of all specimens at seven days after mixing was more than 20 kgf/mm2. It was increased with the increase of palladium and decrease of silver.
3)Shirinkage rates of specimen-length when compressive strength measured which were correlated inversely with compressive strength were 2.9-4.2% and 0.9-3.3% at two and seven days after mixing, respectively.
4)Specimens which could endure the weight of the flow test (JIS) didn't include palladium.
5)Vickers hardness of specimens at seven days after mixing were 117-161. For the effects of added metals, it was clearly decreased, when platinum was added more than 25 wt%.
6)Loss in weight of all specimens by the corrosion in 1% Lactic acid solution ranged from 1.4 to 2.5mg/cm2.
7)All specimens have passed the discoloration test of JIS-T 6108(for dental silver casting alloys).
